In a new study, researchers compared the features of 30 different stingray spines to find out why some break off while others remain sturdy<\/p>\n
Scientists have gained a fascinating insight into how\u00a0stingrays<\/strong>\u2019 iconic spines differ across species and the trade-off between different features.<\/p>\n \u201cStingray spines are highly modified scales,\u201d says Emily Poulin, a PhD candidate at\u00a0UC Irvine.<\/p>\n Found on the tail of the stingray, these spines are used for protection when the ray feels under threat. \u201cWhen they use these spines, they puncture them really deeply into their attacker,\u201d she says. \u201cThey can deliver venom into the wound.\u201d<\/p>\n People often assume that stingrays might attack humans with their\u00a0venomous tail barb but they are purely for self-defence. \u201cThey use their spines as a last resort to protect themselves,\u201d says Poulin. \u201cUsually, they would rather make an escape, if possible.\u201d<\/p>\n Because the rays wield these weapons when being attacked, it\u2019s vital that they work. \u201cIt’s life or death if these tools are effective,\u201d she says.<\/p>\n Poulin and colleagues had noticed that some stingrays have spines that seem to have evolved to break off \u2013 \u201cyou’ll see them wedged in the skeleton of certain sharks or large predatory fishes,\u201d she says \u2013 while others have more durable barbs that stay intact.<\/p>\n In a new study, published in\u00a0Proceedings of the Royal Society B: Biological Sciences, they explored how different features affect performance across 30 different species of stingray.<\/p>\n To do this, they gathered a collection of different spines from various species. \u201cIt’s hard to observe them actually striking,\u201d says Poulin, so the team tracked down specimens from museum collections around the world and used micro-computed tomography\u00a0(micro-CT) scanning to get a high-resolution picture of their key features.<\/p>\n \u201cOur idea was to break down the spines into their mechanical components,\u201d she says. \u201cWe measured properties of the spines that we thought would be important for their defensive function, and\u2026 we basically plotted all of the functional traits that we saw.\u201d<\/p>\n